Does a Mac need a defragmentation?
If so, what freeware program does this best?
When you start working on large media files, you need to defrag your Mac from time to time because it optimizes free space and improves data accessing time. The new version of Mac file system i.e HFS+ has the ability to decrease the chance of fragmentation of up to 20 Mb file size. But, if you need to defrag to large file then so many third party tools available in market. Along with iDefrag I have used a good software Stellar Defrag Drive.
The only tools I know of are iDefrag and Drive Genius
But as an Mac administrator my personal opinion is that you don't really need defragmentation tools on a Mac.
For one the file system used on Macs (HFS+) works very different from those known to Windows users (FAT32, NTFS) and is barely or not noticeable effected by fragmentation.
The second thing is that Mac OS X has sort of an intelligent fragmentation method for files. For example it will not randomly spread pieces all over the hard drive. It will write one part at one location and the second part to the closest possible location without further fragmenting the file. This way you end up having two pieces very close together which can be read almost as in a defragmented space.
Unless your Hard Drive is about 90% full you shouldn't really notice any degradation caused by fragmentation. One exception might be if you regularly copy and delete large or a large quantity of file.
I agree with Mike's recommendation, but, although the Mac is *a lot* better than the PC with regard to fragmentation, some Macs require defragging from time to time. It's just a question of how intensively the hard disc written to. If you feel that your Mac belongs to this category, I suggest you download the demo for iDefrag and see what it can offer you.